Great question John,

In general, medium tension will work the best for 95% of all instruments. The instrument is designed for that amount of pressure, even though the pressure differs from one brand to another slightly.

If you feel like you need more power, you can try with higher tension strings though an adjustment of the soundpost would give a similar response. Problem is that a short soundpost can not be made to increase the pressure without changing position which means that you may need a longer post to achieve this. Higher tension is a trade off and means slower action time and more bow pressure needed.

If you feel as though your instrument is too powerful but hard to play, you may try with lower tension strings, though I tend to prefer reducing the soundpost pressure instead.

Moving the soundpost out or in to change the pressure also changes the tone a bit. More towards the E string is brighter and more towards the G is darker.

Lots to think about. I would stick to medium tension.